Seat suspensions for self-propelled vehicles such as snowmobiles have commonly included a seat that is pivotally connected at its forward end to the snowmobile frame and is supported at its rear end by a resilient suspension mechanism. Various types of air cushions and springs have been used to provide such suspensions.
Due to the fact that snowmobiles are frequently driven on irregular terrain and sometimes over obstacles that are not clearly visible through snow, it is necessary for the seats of such vehicles to provide a satisfactory protective shock absorbing capability. Improvements in such suspension systems continue to be needed because of the trauma that can be caused to the spine of a rider by the shocks transmitted from the seat to the rider's torso.
One problem that has occurred is that resilient means, for example air cushions, that provide a great deal of cushioning of a downwards thrust by the driver's torso into the seat will compress with a great deal of stored force. This force is then rapidly relieved shortly after the shock experienced by the vehicle and rider, to the extent that the rides s torso can be thrust upwardly with great force which may even throw the driver from the vehicle. A similar phenomenon can occur with self-propelled water craft upon falling of the vehicle from the crest of a wave to a trough. A need, thus, exists for an improved seat suspension system for vehicles such as snowmobiles, water craft, etc., particularly of the type designed to be operated by a single driver carrying, occasionally, no more than one passenger.